Process for separating acetone and diacetylene



nited States Patent PROCESS FOR SEPARATING ACETONE AND DIACETYLENE Jesse T. Dunn, Charleston, W. Va., assignor to Union Carbide Corporation, a corporation of New York No Drawing. Filed Dec. 30, 1955, Ser. No. 556,421

12 Claims. (Cl. 260-678) This invention relates to the recovery and purification of diacetylene and more particularly to the separation of diacetylene from admixture with acetone.

In certain industrial processes there is produced an acetone mixture containing substantial amounts of diacetylene. This mixture is an oily liquid consisting of approximately equal amounts of acetone and benzene in which is dissolved diacetylene as well as vinylacetylene, toluene, cyclopentadiene, phenylacetylene and other impurities, such as naphthalene in many cases. Some solids are also presentin this crude oily liquid mixture, probably due to the polymerization of diacetylene. The concentrations of diacetylene in this crude mixture are usually from 4 to 12 percent, well below the 20 percent considered the maximum concentration which can be handled safely in the solution.

Steam distillation followed by ordinary fractionation of such a mixture, for instance by fractional distillation, will separate the diacetylene from most of the impurities and the distillate will comprise an acetone solution of diacetylene. Such a solution of diacetylene in acetone is entirely suitable for use in some reactions. For many other types of reactions, however, the acetone would interfere and must be removed and the diacetylene transferred into another solvent.

Fractional distillation, even in highly eficient columns, is not satisfactory for separating diacetylene from acetone for this separation cannot be accomplished by distillation from solutions of a concentration regarded as safe to handle. It is possible that diacetylene could be separated by highly concentrated solutions of diacetylene .but such procedure is undesirable for two reasons. Concentrations of diacetylene in excess of 20 percent are unsafe and present a serious explosion hazard. Also, the

.heat of distillation applied to such high concentrations will deposit excessive amounts of polymer and is therefore not feasible.

I have discovered, however, that substantially all of the acetone can be removed from admixture with diacetzylene by vaporizing the diacetylene and acetone and scrubbing the vapors with water to dissolve the acetone in the water and leave the diacetylene. The diacetylene thus separated is collected in the desired solvent in the amount of no more than 20 percent of the final solution.

7 The process of the invention can be applied to simple mixtures of acetone and diacetylene as well as to almost any mixture containing acetone and diacetylene regardless of other compounds or impurities that may be present.

'- in the practice of my invention the acetone mixture containing the diacetylene is distilled and the vapors of acetone and diacetylene rising therefrom are contacted with water whereby the acetone vapors are dissolved in the water. In my investigation, I employed a distillation column surmounted by a dephlegmator head to effect. this contact but in commercial operation on a larger scale any suitable apparatus could be employed. It is preferred, though not essential, that the water employed be cooled and that the temperature in the actual scrubbing apparatus be maintained between 10 and C. with about 10 to 25 C. preferred. The degree of recovery of the acetone from the diacetylene vapors will depend to some extent on the quantity of water fed through the scrubbing apparatus. Practical considerations limit the amount of water to be used in this operation and the quantity employed will depend upon the amount of acetone to be recovered as well as, to some extent, the type of scrubbing equipment employed. While it might be possible to employ other liquids of very low vaporpressure in place of water as the extractant, the numerous difliculties which would be encountered 'with other solvents, makes the use of water highly preferable. If other solvents were used the costs would be greater, the process would be more complicated to operate and it would be necessary to recover the solvent.

After scrubbing to remove acetone the diacetylene vapors are cooled and collected in whatever solvent may be.desired with a view to a further use of the diacetylene. The diacetylene should not be collected in greater than 20 percent concentration in this solution. The collecting solvent is preferably cooled to a temperature between 40 and 10 C. with about 0 C. being optimum, so as to collect the diacetylene vapors without the danger of collecting flammable diacetylene vapors out of .solution. The particular collecting solvent to be employed will depend upon further use to be made of the diacetylene. Suitable solvents include such alcohols as methanol, ethanol, butanol, Z-ethylbutanol and other allylalcohols, as well as glycols, ethers, esters, ketones, chlorinated hydrocarbons such as carbon tetrachloride, diethyl carbitol and ethylene glycol, as well as many other organic solvents. The extractive distillation process of the invention can be performed either as a batch or continuous operation. Certain advantages accrue from continuous operation. In such operation, the shorter residence time of diacetylene in the heat zone reduced the extent of polymerization to potentially hazardous substances and increases the percent of recovery of diacetylene. In continuous operation the use of heat exchange equipment would make it possible to employ larger volumes of water more economically and thus more thoroughly remove the acetone.

Solutions of diacetylene refined according to my invention contains vinylacetylene in addition to small amounts of water and acetone. The presence of some vinylacetylene is of little consequence. In most instances, vinylacetylene does not react under the conditions under which diacetylene is reacted. However, when necessary, the amount of vinylacetylene can be greatly reduced or substantially eliminated by prestripping the original. solution by distillation to remove the vinylacetylene. The acetone content can be reduced by employing greater volumes of water as discussed above and water can be removed by the use of conventional inert drying agents.

The process of the invention can be applied to simple mixtures of acetone and diacetylene as well as to almost any mixture containing acetone and diacetylene regardless of other compounds or impurities that may be present.

The following examples are illustrative of the invention:

Example I A fractional distillation apparatus was assembled consisting of a oneinch diameter vertical glass column l8 inches in length and packed with glass helices, the-cob umn being connected to the top of a kettle. A dephlegmator head at the top of the column was equipped with a water inlet to permit feeding a stream of water down the .columnwA vent from the dephlegmator head was connected to a receiver vessel cooled in ice and contain- 3 p i-ii'g-diethyleneg1yco1 dieth'yl'ether as a solvent. The kettle waseharged with-1.5literofa crudesolution containing by weight 8.3 percent of diacetylene and 1.1 percent of vinylacetylene dissolved in a liquid comprised prificipally er acetone and benzene -and f having sriiall aments of other contaminants s'uch as toluene, cycloeatadiene, styrene, phenyla'cetylene aiid' the like. As the="t':rude st'rl'ution in the kettle was heated t'o boiling, Water was fed into'the dephlegmator head and thence dwn the'coluinn at 'a rate ef from 1 to 1.5 liters per Bel-Jr. Water was-alsopassed through the dephleg'niato'r 7 eau rer iiadir t i n g: v rs m e 'Distillation was :iaaisetaeaatsu h rate that substantially all 6f the reeover'able 'diacetylene was :paieaembsut 1 hour. During this -'pe'r'iod' 'the de- 134Elegisl te/torhead temperature rose fro'm 25 to afinal temperatnreer sbeut 45 C. The product'in the racer ter. The recovery was approximately 85 percent.

Exampl III .A ifractional distillation apparatus was assembled con- '$iSfiIlgfOfia' one inch diametervertical-glass column 3 :feet'i'n-length and packed with glass heliees,'-the-col1mn :beiugconnected to the top ofa kettle. A deph-le'grna- :'to1" Qhead-atthe'top of the column'was equipped with a *waterinlet to permit feeding a stream of water down the icolumn. -A vent from thedephlegmator head was connected to a receiver vessel cooled in i'ce and containing methanol asja solvent. The kettle was'char'ged with 1.5 liters of a-crude solutionicontaining byweightll percent .cofidiacetylene' and 122 percent of ilin'ylacetylene dissolved in a liquid comprised principally of acetone and benze'ne -and having smaller amounts 'of other confaniinantsfs uch Las toluene, cyclopent'adiene, styrene;phenylacetylenv lheilike. The crude solution inthe kettle' was heated to. boiling and water wasfed into'the dephlegm'a'tor hejad =and thence'down the columnat a" rate of {mm 1*tof1l5 .liters per hour. A refrigerant was also passed through i the dephlegmator' head for indirect cooling of the vapors -fiom theicolumnf Distillation was mainta'inedat such :a' rate ithat substant-ially all of the recoverable diacetylene V fWas distilled and passed through'the'dephlegrnator'head sin a period of about 1 hour. During this-periodthe temperature of the 'dephlegmator 5 head :was'. ni'aintain'ed :between and '15 C. The productimthe'rec'eiv- =-er vessel was found to contain by weight 14.1 percent diacetylene,;2.1 percent vinylacetylene and- Q.16'percent' .acetone. The recovery was approximately 75 percent.

'What is claimed is:

p 1. :A process for separating diacetylene. from arliqui d mixture containing diacetylene and acetone which comprises heating said mixture at a temperature sufli'ci e n tly velevated to cause evolution of vapors of said diacetylene and said acetone,'-'w'ashing said vapors withwa'te'r tof' dis- "s'ol've' said acetone vapors-in said water andco olingfand 'eollctingsaid diacetylene vapors. V 7

24 A process for separating diacetyl'ene froni-"a liquid "mixturecbntaining' diace'tylefie" and acetone which com- -'heatirlg said mixture-at a teiiiperatufe 'sufiic nfly elevated to cause evolution of" va ors of' diac tvlene' and acetone from said mixture, washing said vapors with water to dissolve said acetone vapors-in---said water, and cooling and collecting said diacetylene vapors in a solvent.

3. A process for separating diacetylene from a liquid 6 mixture containing diacetyleue and acetone which comprises heating said mixture at a temperature suln'ciently elevated to cause evolution of vapors of diacetylene and acetone from said mixture, washing said vapors with waterat a temperature between 10and 90 to dissolve 10 said acetone vapors-ims aid water,'-a1id cooling and collect- :ing'said-diacetylene vapors ina solvent. H 4 V 4. A process for separating diacetylene'frorne 'liquid mixture, containing diacetylene and acetone which comprises heaa'ag sat-a mature at a temperaturesumeinu elevated to cause evolutic n :of va pors ofdiacetylene and V acetone from said mixture, washing said vapors with water at a temperature between 10 and 25 C. to dissolve said acetone vapors in said water, and coolingand col.-

'-"1eetii ig=s'aiddiacetyleneina-solvent; g 5. A piocess'for separating. diacetylene fi'ont. quid mixture containingdiacetylene and acetone which eempris e's' heating 'said mixture at :a temperature s'ufiiciently i elevated to "cause evolutien of vapore of d; c'e'tylene -and e acetone from said mixture, washingsaid-vapors'with water to dissolve said acetone'vapors in saidwvater afid cooling and collecting said-aiactyie eva ors-ma:servant *atia tem erature between 40-and -1'0- c.- H

6; A' process for. separating dia'cetylene from -a=nquid mixture containing diaeetylene and acetone' which cotn- -prisesheatingsaid mixture -at-a temperature 'sufliciently elevated tocztuse evolution of; vapors-o?diacetyleiie and acetone from-said mixture; washing 'said vaporswith at'er to dissolve said acetone vapors in. said I water; zan d cooling and collecting said diacetylene vaporsina s'o1vent jat a-tenrperature-ofabout0 C;

"7.- A-pro'cess for,separatingdiac'etylene fromalr'acetoiie 'solution' containing diacetylen'e, and {other "higher bolling impurities; which process comprises heating' saidsolution'at' a temperature siifficiently elevate 'd 'to'c'ause ever 40 tion dfvaporsof diacetylene-aiid acetoiie from iture; washing said vapors water' to dis'soivefl aid "acetone vapors in said waterrancl cooling and colletin g said diacetylenevapors. v I i if '*'8;A process for separating diac etvlene fronf acetone so1utioncohtaining diacetyle'ne asadisarmamenimpurities; which process -comprises nee g" aid lselu- Z'tion" at a teniperalture sufliciently elevated tocau v .diacetyleneand-aceton V d vapors with water to cli pors-i in said water, cooliig'g and; collecti a t l a pis' aa ms {9. Ajprqces's' forsiepa'rating fiiacetylen-firom tone solution containingjdiacetylene' and other ing impurities; whichpi'oces's' comprises-heating said soli1- .tion at a. temperature sufiiciently elevated'to eause ismtion'of vapors "of 'diacetyle'ne acetone? frotn 's'ai mixjture', washingsaidvapors .wfth wate r at' a temperature me ento and v90 tofldis'solvesaidacetone vapors 60 firrsaid ater, 'and'cooling aud 'collecting' said sisee'tyiene apb is m f f.10. roce'ssforseparating'diacetylene 1 tone' sfolution' containing diacetylenearid Ofhe b ling; which proces's amputees 's ffltlfipfli at; a"temperature-sulficientlvelevat d t'o 'evolutionfofvapors"of rdiacetylene an 'cetone" r'nixturey'washing said vapors"with j bet ween lfl an j 'j V g r =vapors in =said water,- ai:ic1; coolirig 'and -colleet 11g. f(iiacetylene-vaporswinasolvent. f

d lrfl processforseparating diacetyle i e' s ution-containing diacetylene boiliiig i111purities;-whichproeess' compri *solution'at a tempera u e sumetessyeievatea emains of vapo rs"ofdiacetvlene an ace am l mebwashingsa'idvaporswith? are: -t'of'dissolacetone vapors in said water, and cooling and collecting said diacetylene vapors in a solvent at a temperature between --40 and 10 C.

12. A process for separating diacetylene from an acetone solution containing diacetylene and other higher boiling impurities, which process comprises heating said solution at a temperature sufiiciently elevated to cause evolution of vapors of diacetylene and acetone from said mixture, washing said vapors with water to dissolve said acetone vapors in said water, and cooling and collecting 10 said diacetylene vapors in a solvent at a temperature of about 0 C.

References Cited in the file of this patent UNITED STATES PATENTS Curme July 11, 1922 Scott et a1. Feb. 7, 1939 Taylor Apr. 1, 1941 Deanesly July 21, 1942 FOREIGN PATENTS Great Britain Aug. 17, 1934 

